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The overarching objective of the study is to determine the effectiveness of LMWH/ warfarin vs. DOAC anticoagulation for preventing recurrent VTE in cancer patients. The intervention strategy is Direct Oral AntiCoagulants (DOAC) therapy with edoxaban, apixaban, rivaroxaban, or dabigatran. The comparator is low molecular weight heparin (LMWH) alone or with warfarin. The information gained will empower cancer patients and physicians to make more informed choices about anticoagulation strategies to manage VTE.

Venous blood clots affect nearly a million Americans each year. Venous clots in the legs are called deep venous thrombosis (DVT) and are dangerous because they travel to the lungs where they cause blockages known as pulmonary emboli (PE). DVT and PE are called venous thromboemboli (VTE). Cancer is a risk factor with nearly 200,000 VTEs in cancer patients each year. The purpose of VTE treatment is to prevent the initial clot from spreading and to prevent new clots from forming. This is accomplished by thinning the blood, or anticoagulation. Without anticoagulation, VTEs recur and are often fatal.

Recently, the FDA has approved 4 new Direct Oral AntiCoagulants (DOACs) for preventing VTE recurrence. Few cancer patients were included in the efficacy trials, and practice guidelines fall silent on whether switching to DOAC therapy is advisable. To fill this knowledge gap, the Alliance Foundation Trials LLC, a research network of academic and community practices across the US, is conducting a pragmatic randomized effectiveness trial.

The overarching objective of the study is to determine the effectiveness of LMWH/ warfarin vs. DOAC anticoagulation for preventing recurrent VTE in cancer patients. The investigators will conduct a trial of 940 cancer patients followed for 6 months. The intervention strategy is DOAC therapy with edoxaban, apixaban, rivaroxaban, or dabigatran. The comparator is LMWH alone or with warfarin. Within each arm, patients can choose the agent they prefer based on side effects, drug interactions, and practical issues such as co-pays. The trial compares these two strategies in terms of treatment: 1) benefits based on VTE recurrence; 2) harms based on bleeding rates; 3) burdens based on patients' reports of their experiences; and 4) mortality rates.

The investigators hypothesize that the benefits, harms and burdens of DOAC treatment will be non-inferior to, or better than, usual care with LMWH/ warfarin among cancer patients. The information gained will empower cancer patients and physicians to make more informed choices about anticoagulation strategies to manage VTE.

Randomized Arm 1 will get anticoagulation therapy with a Direct Oral AntiCoagulant (DOAC). There are four FDA-approved DOAC drugs that may be used for this study: Rivaroxaban, Apixaban, Edoxaban, or Dabigatran. The treatment (including dosage form, dosage, frequency and duration) should be administered in accordance with the drug's FDA package insert, and all modifications are at the discretion of the treating investigator.

Drug: Rivaroxaban

Anticoagulation therapy.

Other Name: Xarelto

Drug: Apixaban

Anticoagulation therapy.

Other Name: Eliquis

Drug: Edoxaban

Anticoagulation therapy.

Other Name: Savaysa

Drug: Dabigatran

Anticoagulation therapy.

Other Name: Pradaxa

Active Comparator: Randomized Arm 2

Randomized Arm 2 will get anticoagulation therapy with low molecular weight heparin (LMWH) with or without a transition to warfarin. There are three FDA-approved LMWH drugs that may be used for this study: Dalteparin, Enoxaparin, or Fondaparinux. The treatment (including dosage form, dosage, frequency and duration) should be administered in accordance with the drug's FDA package insert, and all modifications are at the discretion of the treating investigator.

Drug: Warfarin

Anticoagulation therapy.

Other Name: Coumadin

Drug: Dalteparin

Anticoagulation therapy.

Other Name: Fragmin

Drug: Enoxaparin

Anticoagulation therapy.

Other Name: Lovenox

Drug: Fondaparinux

Anticoagulation therapy.

Other Name: Arixtra

Experimental: Preference Cohort

If an eligible participant is offered randomization and declines randomization, then a limited number of participants (up to N=190) will be allowed to enroll in the Preference Cohort. In this case, the treating physician and patient choose Arm 1 or Arm 2 (non-randomized).

To compare the effectiveness of anticoagulation with a DOAC (intervention) with LMWH/warfarin (comparator) for preventing VTE recurrence in patients with cancer based on cumulative VTE recurrence reported by patients or clinicians at 6 months.

Choosing to participate in a study is an important personal decision. Talk with your doctor and family members or friends about deciding to join a study. To learn more about this study, you or your doctor may contact the study research staff using the contacts provided below. For general information, Learn About Clinical Studies.

Diagnosis of VTE <= 30 days prior to study enrollment for which potential benefits of anticoagulation therapy to prevent recurrence of VTE are felt by the treating physician to exceed the potential harms

Any anticoagulation drug/strategy may be used to treat the index VTE; protocol treatment will begin <= 30days after the index VTE diagnosis date

Treating physician intends to put participant on anticoagulation therapy for at least three months.

Individual-level de-identified datasets will be made available to investigators working under an institution with a Federal Wide Assurance (FWA) who formally submit a request to Alliance Foundation Trials LLC (AFT). Prior to the release of datasets, AFT ensures certain requirements, e.g., IRB approval and data use agreement, are in place. These datasets will be available within 6 months of publication of the manuscript and following a formal request by an investigator to and approval from AFT.